Not one, two or three… No, the new X5 M50d makes use of four turbochargers, and the results are astonishing...

You can’t really miss those kidney grilles, can you? They dominate the new X5’s face, as they do the X7 and facelifted 7 Series.

On the X5 M50d, however, they exist for a good reason: four blowers need a lot of cooling air, especially when they have enough punch to propel the vehicle in question to our quickest-ever 0-100 km/h sprint in a turbodiesel-engined test car. Despite registering a significant 2 377 kg on our scales and the engine displacing a fairly modest 3,0 litres, the flagship X5 needed a scant 5,01 seconds (beating BMW’s claim by 0,19 seconds) to break through the three-figure barrier on our test strip; and just 3,51 seconds to leap from 80 to 120 km/h. What wizardry has BMW’s engineers applied to achieve such impressive performance?

Multi-stage turbocharging, mainly. The system comprises two high-pressure and two low-pressure turbos affording a quick build-up of charge pressure from down in the rev range (450 N.m is delivered at 1 000 r/min, for example). During normal driving conditions, both low-pressure units and one high-pressure turbo are active. When the virtual rev needle passes 2 500 r/min, the remaining blower spools up.

The result? Stupendous response anywhere in the rev range – we can’t recall another turbodiesel reacting this quickly – and slingshot acceleration even at illegal velocities, the ZF-sourced eight-speed torque-converter transmission (one of the best in the business) zealously firing through its ratios.

The inline-six even sounds good. Despite being quite obviously a turbodiesel in its mechanical clatter, thanks to some clever trickery through the audio system, the M50d has a old-school muscle car rumble that, if it seems too artificial (it does, especially near the 5 000 r/min redline, where the buzz intrudes), can be muzzled via the drivetrain-management software.

Equally impressive as its punch is its parsimony, this heavily optioned test unit sipping just 8,4 L/100 km on our combined-cycle fuel route. If this is one of the last of the performance diesels before electric drivetrains swarm the market, it’s an incredible swansong.

Let’s not get carried away, though, as there’s much more to a performance SUV than an engine; they have to go round corners, too. This fourth-generation X5, launched 20 years after that beloved first edition, sits on a heavily revised platform running adaptively damped steel coil suspension. Our particular test vehicle boasted Adaptive M suspension Professional, which for R52 000 adds active roll stabilisation – it uses electric swivel motors to rein in body roll under hard cornering – plus Integral Active Steering (effectively four-wheel steering). The result is a vehicle that goes around corners like it weighs a few hundred kilograms less, but also one that favours ultimate stability and traction (no wonder given the fat 315-wide rubber on the rear axle) over enjoyment. That said, the rear-end can be provoked into the occasional wiggle.

Some team members had their reservations about the Integral Active Steering system, noting it feels overly light in comfort mode and somewhat stodgy in the sport settings, with very little feel and feedback apparent through the rim. The brakes, however, were beyond criticism, halting the 2,4-tonne SUV in an average of 2,83 seconds over 10 punishing emergency stops. Credit to the massive ventilated discs.

And what of the ride, considering this has to function as a comfortable family vehicle, too? Well, despite sitting on ultra-low profile tyres wrapping heavy (and, therefore, difficult-to-control) 22-inch wheels, the X5 M50d does a broadly impressive job of keeping an even keel. The ride’s certainly firm, however, and it might be worthwhile considering the optional (R18 100) two-chamber air suspension system; our experience with a X5 30d so equipped suggests rolling comfort is enhanced with the air springs.

The fantastically comfortable, ahem, comfort seats fitted here at R12 600 certainly do their part to cushion blows. They’re widely adjustable, enveloping without being overly soft, broad enough for all shapes and a worthwhile swap over the standard-fitment, less-yielding sport seats. They’re trimmed in silky soft Merino leather in a coffee hue that extends into the door cards and elbow rests; the rest is thankfully covered in a more restrained black.

And restraint is certainly needed when speccing an X5, unless you lean towards the lurid end of the spectrum. The eight-member CAR test team agreed the options-sheet box for the R9 400 CraftedClarity package, with glass finishes on the gearlever, iDrive controller and elsewhere, should be left unticked; the standard items look great and are crisply rendered anyway.

Perceived quality is superb (aside from one glaring part: the sliding cover for the central cubby was sticky on both X5s we tested) and the iDrive 7.0 system is as easy to use as always – the 12,3-inch central screen is now touch-responsive. A screen of similar size subs in for analogue instrumentation and corrals the dials into odd rhomboid shapes you’re either going to love or loathe (we were split, but will spare you the clichéd “we miss BMW’s simple, beautiful instrumentation”).

Aft, there’s lots of room for two adults – and three at a pinch – with a measured 724 mm of legroom matching what we achieved with the Audi Q7 and Volvo XC90 despite the BMW’s second-row bench being fixed (a seven-seat option will be offered). That’s no surprise, considering the latest X5 has grown 42 mm in its wheelbase and 36 mm nose to tip. There is good headroom, too, although the optional panoramic sunroof robs a few millimetres, while the boot is sufficiently spacious at 384 litres yet smaller than an XC90’s 464 litres.

In terms of safety, the new X5 ticks the boxes for collision and pedestrian warning plus city braking. Additionally, this model has lane-departure and lane-change cautioning as standard over and above the 30d’s spec sheet. BMW’s Driving Assist Professional with a whole suite of active safety items is a R21 900 option on the M50d.

It doesn’t want for standard specification otherwise; adaptive LED headlamps, four-zone climate control, head-up display, electrically adjustable heated seats and Live Cockpit Professional with sat-nav and internet services are included.

TEST SUMMARY

It’s a bold statement of intent by BMW to launch a new performance turbodiesel engine at a time when the future of internal-combustion engines is fraught.

But it’s a gamble that’s paid off. Few – if any – powertrains can match this combination of dazzling mid-range grunt and relative frugality, shrugging off the disappointing weight of BMW’s new SUV without making you pay at the pumps.

You’ll pay at the dealership, though. While R1,5 million is comparatively good value for money considering where Jaguar Land Rover SA pitches the slower but equally sophisticated Range Rover Sport SDV8, we’re convinced the sweet spot in the X5 range lies with the 30d, which is R300 000 less. Sure, you lose some spec and performance (although not as much as you may think), but its gentler approach suits the new X5’s refined manner better.